2- Créer le projet dans Google Developers Console

In the first time, you do not have any Project, so you have to create it. In most cases, you should name Project same your Website name (It is not compulsory).

Project Name:
ExampleWebsite

Project has been created:

Goto
"APIs and auth/Consent screen", to create a Product Name.

Create Client ID:

In case you use
OAuth2.0 on a web application, you will have to create ClientID for that web application. Parallel, you declare the redirecting link (The link will be redirected to after user logs in his/her google account and allows your application to connect with Google OAuth).

ClientID is created, in which the two most important kinds of information are
Client ID and
Client Secret. You need to have it in Java code (Illustrated in the following example).

​Note: You can create multiple
ClientIDinformation for your different applications.